In depth investigation of the spatial variations of DOM components in sediments under the influence of cascade dams and their interactions with microbial communities

Cascade dams drive the accumulation and transformation of dissolved organic matter (DOM) in sediments, altering microbial community composition and thereby disrupting watershed ecosystem integrity and functionality. However, the spatiotemporal dynamics of sediment DOM components in small cascade-dammed watersheds and their interactions with microbial communities and metabolic traits remain poorly characterized. This study investigates the Xixi River (China), a representative small cascade-dammed watershed, by integrating three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy with parallel factor analysis (PARAFAC), co-occurrence network modeling, structural equation modeling (SEM), and functional gene prediction. We systematically quantify linkages between DOM components and microbial communities across hydrological seasons and elucidate relationships between microbial metabolic traits and DOM dynamics.